The principal objective of the proposed research is to define the multienzyme systems involved in the regulation of the composition, rate of synthesis and secretion of carcinoembryonic antigen in tumor tissues. This process will be examined in structural studies, and in studies of individual enzymes and particulate multienzyme systems. The structure of the oligosaccharide chains of CEA will be determined by periodate oxidation, hydrolysis with specific glycoidases and examination by gas chromatography. Individual sugar residues will be sequentially removed from the glycoprotein with highly purified glycosidases to prepare glycosyl acceptors which will be used in biosynthetic studies with cell-free preparations isolated from primary tumors of the colon, breast and pancreas. This process will also be studied with isolated cells in culture in order to examine the influence of serum components and diferent cell membrane glycoproteins on the rate of synthesis and composition of the oligosaccharide moiety of CEA. The study of these processes with both in vivo and in vitro systems will aid in the understanding the possible role of CEA in metastatic dissemination of tumor cells. The interaction of purified carcinoembryonic antigen and derivatives devoid of specific sugar residues with other macromolecules present on the tumor cell surface and in the circulatory system will be examined. These studies will attempt to determine whether the antigen is involved in the organization of macromolecules on the tumor cell surface or interacts with specific lectins in serum.